HELSINKI/OSLO, April 10 (Reuters) - The start-up of Finland’s long-delayed Olkiluoto 3 nuclear reactor is likely to be pushed back by at least another two months, its project director said on Wednesday.

The reactor in western Finland, built by a consortium of France’s Areva and Germany’s Siemens, is already more than a decade behind schedule and had been due to start producing electricity in January 2020.

However, operator Teollisuuden Voima (TVO) said that modification work during the first quarter had not progressed according to schedule.

This means the loading of nuclear fuel into the reactor will now be pushed back by at least two months, to August from June, it added.

“This new schedule review informed by the plant supplier is disappointing of course,” it said in a statement.

Changes to automated systems had been made and needed to be checked, which took longer than expected, said project director Jouni Silvennoinen.

He told Reuters the fuelling delay would likely postpone the start-up of regular electricity production by an equal number of months.

Prior to Wednesday, the most recent delay to the project was announced in November 2018, as a result of which TVO was entitled to a payment of 18 million euros ($20 million) from Areva.

Silvennoinen said the financial impact of the new delay would be clarified when the plant eventually started producing electricity regularly.

In March, Finland’s government issued an operating permit for the 1.6 gigawatt Olkiluoto 3 reactor, one of the final requirements to allow the plant to start up in 2020.

Olkiluoto 3 still requires a final licence from nuclear regulator STUK to allow it to load fuel and start production.